The role of epidemiology in cancer prevention

1. ISA Brown and Shaver 288 pullets were changed from 8 h to 8, 10, 13 or 16 h photoperiods at 42, 63, 84, 105, 126 or 142 d of age. 2. Age at first egg (AFE) was curvilinearly affected by the size and timing of the change in photoperiod. AFE was advanced most by a photoperiod change from 8 to 13 h made at 63 or 84 d. ISA birds were generally more responsive than Shaver to the photoperiod changes. 3. Longer photoperiods significantly increased survivors' egg production, but decreased liveability to 504 d. so that eggs per hen housed were unaffected. Retarding AFE by 10 d reduced survivors' egg numbers by 7.0, but increased mean egg weight by 1.26 g. Egg output by Shaver birds was unaffected by AFE, but that of ISA was curvilinearly affected, with an apogee at an AFE of 135 d. In both breeds, egg weight and egg output were greater following an early or late, rather than a mid-term photostimulation. 4. Photoperiod significantly increased mean daily food intake during lay by 1.26 g/h. A 10 d retardation in AFE resulted in a reduction in food intake of 1 g/d. Efficiency of food conversion deteriorated according to the square of the photoperiod, and changed curvilinearly according to age at photostimulation. Food conversion efficiency improved by 0.05 g/g for each 10 d delay in AFE. 5. Shell quality was unaffected by AFE, but deteriorated with increasing photoperiod and was curvilinearly affected by age at photostimulation with the smallest shell weights associated with photostimulation at 63 d. The incidence of double-yolked (DY) egg production increased with photoperiod and decreased with delayed photostimulation. There was an exponential regression of DY eggs on AFE. 6. Body weight at first egg increased by 75 g/d delay in AFE, but body weight at 504 d of age was unaffected by AFE, photoperiod or age at photostimulation. Body weight gain during lay increased by 15 g/h increase in photoperiod, decreased by 6 g per 10 d delay in photostimulation and by 40 g per 10 d delay in AFE. Fat content at 504 d increased by about 10 g/kg and by 23 g/bird for each 10 d delay in AFE. 7. Mortality in lay increased by 0.8%/h increase in photoperiod, but was unaffected by either age at photostimulation or AFE.     

Circulating soluble adhesion molecules E-cadherin, E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in patients with gastric cancer

The concentrations of the soluble adhesion molecules E-cadherin, E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were investigated in 45 patients with gastric cancer before treatment and their correlation with clinical, histological and routine laboratory parameters was examined. Data were collected on tumour stage at presentation, presence and sites of metastatic disease, tumour pathology, survival and results of routine laboratory tests. Serum concentrations of ICAM-1 and VCAM-1 were significantly elevated in the patients with gastric cancer in comparison with the group of healthy subjects (P < 0.00001 and P < 0.0001 respectively). Increased serum concentrations of VCAM-1 were associated with locally advanced and metastatic disease whereas ICAM-1 was significantly elevated both in local and in advanced/metastatic disease. Soluble E-cadherin and E-selectin concentrations did not show any significant elevation in gastric cancer patients. Concentrations of soluble adhesion molecules showed significant correlation with each other (except E-selectin and VCAM-1) and with alkaline phosphatase. Soluble ICAM-1 and VCAM-1 were significantly associated with an elevated total white cell count. Patients with elevated VCAM-1 had significantly poorer survival in comparison with patients with normal serum levels (P = 0.0361).     

Recombination and loss mechanisms in low-threshold InAs-GaAs 1.3-/spl mu/m quantum-dot lasers

We show that even in quantum-dot (QD) lasers with very low threshold current densities (J/sub th/=40--50 A/cm/sup 2/ at 300 K), the temperature sensitivity of the threshold current arises from nonradiative recombination that comprises /spl sim/60% to 70% of J/sub th/ at 300 K, whereas the radiative part of J/sub th/ is almost temperature insensitive. The influence of the nonradiative recombination mechanism decreases with increasing hydrostatic pressure and increasing band gap, which leads to a decrease of the threshold current. We also studied, for the first time, the band gap dependence of the radiative part of J/sub th/, which in contrast increases strongly with increasing band gap. These results suggest that Auger recombination is an important intrinsic recombination mechanism for 1.3-/spl mu/m lasers, even in a very low threshold QD device, and that it is responsible for the temperature sensitivity of the threshold current.     

Experimental analysis of temperature dependence in 1.3-μmAlGaInAs-InP strained MQW lasers

We have analyzed experimentally the temperature and pressure dependences of the lasing characteristics of 1.3-μm AlGaInAs-InP strained multiple-quantum-well lasers, by focusing on the ratio of the nonradiative recombination current to the total current. The temperature dependence of the radiative current was studied by observing the spontaneous emission through a window in the substrate. It was found to increase linearly with temperature, exactly as expected for an ideal quantum well over the entire temperature range from 100 to 360 K. Further, it was shown that pure radiative recombination dominated the total current below a breakpoint temperature T_b of 220 K. Above this temperature, the onset of loss processes including Auger recombination caused a superlinear increase in the threshold current. Analysis of the linear and nonlinear components allowed us to determine the ratio of the nonradiative to radiative currents at threshold. We find that, relative to similar GaInAsP/InP lasers, there is a decrease in the nonradiative component of the current, resulting in a higher characteristic temperature T₀ in the AlGaInAs-InP lasers. At 300 K, the radiative recombination current is more than 70% of the total threshold current. This result is consistent with the observation that the threshold current increases by about 8% in 12-kbar hydrostatic pressure, while in GaInAsP lasers, a decrease of 10% or more is always observed over this pressure range     

Practical Magic

Typically, Doherty test fixtures are inflexible with regard to combiner positioning. The generic Doherty development fixture shown here can quickly provide the designer with the final circuit requirements for multiple devices. The dynamic Doherty combiner enables this flexibility by using the 50-Omega line as part of the output transformation. An easy-to-implement 50-Omega line and a shunt cap provides the transformation required from the Doherty inverter to the amplifier output. Final circuit configurations can revert to the traditional lambda/4 transform once the phase length "Oslash" is identified. Flexible Doherty development circuits will assist in minimizing the fixtures required for development efforts. This Doherty development process is easy and straightforward to implement, and results can be obtained quickly. Simulation methods and models will continue to be used to create the 50-Omega tuning structures and optimize the design of Doherty circuits. However, this practical design approach can be applied for each circuit that needs to be designed, and good results will be obtained.     

Forces required to jettison a simulated S92 passenger exit: Optimal helicopter underwater egress training techniques

This paper outlines the first known examination of the forces required to jettison a simulated exit used during helicopter underwater egress training (HUET). To capture the forces placed on the simulated cabin exit, a purpose build force plate was designed to replace an existing simulator exit used during HUET. A 25-point map was created to identify specific jettison forces required across the entire exit surface. Ten participants completed a total of 120 underwater egress sequences in–air and in-water from a normal flight and fully compressed crash attenuating seat position. The results indicate that the force required to jettison the simulated exit is significantly different in relationship to location on the exit surface. From the results, it can be concluded that helicopter underwater egress training protocols should ensure that offshore candidates are informed of the different force requirements as well as have the opportunity to practice jettisoning a high physical fidelity exit from a fully compressed crash attenuating seat.     

Minor and major lip reconstruction

Lip reconstruction has made significant advances over the past two decades with refinement of some old techniques and the introduction of new innovative methods. Small and medium defects can be repaired in a variety of ways with similar results. Local lip switch flaps are far superior to any distant tissue. Total lip loss is probably best handled with nasolabial flaps. Extensive resections including the lip, premaxilla, mandible, and skin of the chin and upper neck remain a challenge with all modern techniques, including myocutaneous flaps and free flaps, having little advantage over the standard visor forehead flap.